I too get the same error that Geremia gets, on two different linux boxes both running OpenSUSE Tumbleweed and KDE. Neither machine uses NVidia graphics hardware.(*) I am also using latest Calibre (5.37) as of this post, with the usual linux-installer.sh binary install, as at
https://calibre-ebook.com/download_linux (which I've used for years). My calibre is installed locally in /opt/calibre (i.e. not on a networked drive). I do not get the libiconv.so.2 error message, as in the screenshot below, and /opt/calibre/lib/libiconv.so.2 does exist on my system. I also don't spot anything in systemd logs.
Anyway, here is
a screenshot, if it will help.
As you can see, ebook-viewer crashes even before opening a book.
Let me know if there is any additional information I can supply.
(*)
1. Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics]
2. Advanced Micro Devices, Inc. [AMD/ATI] Turks XT [Radeon HD 6670/7670]